Sewing machine with a light barrier

Abstract

A sewing machine with a light barrier used to detect the edge of a workpiece has an optical light guide ( 17 ) connected to the light source ( 15 ). The optical guide ( 17 ) is arranged in the thread guide hook ( 12 ). The thread guide hook ( 12 ) is fastened to the front side of the head ( 4 ) of the housing and is designed as a small tube for this purpose.

What is claimed is:  
     
       1. A sewing machine with a light barrier, the sewing machine comprising: 
       a light source;  
       an optical light guide;  
       a lens arranged in a head area of the sewing machine;  
       a light receiver for detecting the edge of a workpiece in the area of a stitch formation site, said light source being connected via said optical light guide to said lens; and  
       a thread guide hook located in a vicinity of a thread-tensioning device, said thread guide hook comprising a small tube, said optical light guide being led through said thread guide hook, said lens being arranged on an obliquely downwardly directed free end of said thread guide hook.  
     
     
       2. A sewing machine in accordance with  claim 1 , wherein said lens is accommodated in a threaded sleeve arranged adjustably on said thread guide hook. 
     
     
       3. A sewing machine with a light barrier, the sewing machine comprising: 
       a baseplate;  
       a column connected to said baseplate;  
       an arm connected to said column;  
       a head connected to said column;  
       a thread-tensioning device connected to said head;  
       a light source;  
       an optical light guide;  
       a lens arranged in a head area of the sewing machine;  
       a light receiver for detecting the edge of a workpiece in the area of a stitch formation site, said light source being connected via said optical light guide to said lens; and  
       a thread guide hook located adjacent to said thread-tensioning device, said thread guide hook comprising a small tube, said optical light guide being led through said thread guide hook.  
     
     
       4. A sewing machine in accordance with  claim 3 , wherein said lens is accommodated in a threaded sleeve arranged adjustably on said thread guide hook. 
     
     
       5. A sewing machine comprising: 
       a stitch formation site;  
       a sewing head forming stitches with said stitch formation site;  
       a thread guide arranged in said head;  
       an optical light guide extending through said thread guide;  
       a light source connected to one end of said light guide;  
       a lens connected to another end of said light guide;  
       a light receiver arranged at said stitch formation site and detectable of an edge of a workpiece in said stitch formation site.  
     
     
       6. A sewing machine in accordance with  claim 5 , wherein: 
       said thread guide includes a tube;  
       said light guide is arranged in said tube.  
     
     
       7. A sewing machine in accordance with  claim 5 , further comprising: 
       a thread-tensioning device arranged adjacent said thread guide.  
     
     
       8. A sewing machine in accordance with  claim 5 , wherein: 
       said light receiver receives light from said lens to detect the edge of the workpiece.  
     
     
       9. A sewing machine in accordance with  claim 6 , wherein: 
       said light receiver receives light from said lens to detect the edge of the workpiece.  
     
     
       10. A sewing machine in accordance with  claim 5 , wherein: 
       said lens is accommodated in a threaded sleeve arranged adjustably on said thread guide.